When Mr. Obama said the use of chemical weapons in Syria would mark a "red line" that Assad wouldn't be allowed to cross with impunity, McCain said, "he didn't say, 'It's a red line - and by the way I'm going to have to seek the approval of Congress.' He said it was a red line, and that the United States of America would act. And that's a big difference, and that's one of the reasons why this is so problematic."

The president's decision to take his case for direct involvement in Syria's two-year-old conflict to Congress marked an abrupt turnaround for the White House, which had appeared on the cusp of ordering U.S. forces to launch a missile attack against Syria, in light of evidence that Assad's regime used chemical weapons against his own people.

One of the loudest critics of the administration's handling of Syria, McCain said the president should have taken action early on in the two-year-old conflict. But with "unprecedented leaking" about what ships and missiles the United States have positioned in the region, he argued, "a reversal at this point, I think, has serious consequences as far as the steadfastness and purpose of this administration."

McCain said in order for him to get behind the president's resolution, "we have to have a plan, it has to be a strategy; it can't just be, in my view, pinprick cruise missiles." Still, he warned, "the consequences of the Congress of the United States overriding a decision of the president of the United States of this magnitude are really very, very dangerous."

Sens. Saxby Chambliss, R-Ga., and Tim Kaine, D-Va., appearing later on the program said they back the president's decision to bring the matter to Congress.

"I was supportive of the president taking early action, but he hasn't done that - and now that it's been delayed this much, I think that Congress does have a role to play here," Chambliss said. But he predicted a "very, very tough debate" contingent on Mr. Obama's ability to detail his strategy.

"I would say if the president cannot make his case to Congress then it's not going to pass," he said. "He's got to come out and really be in-depth with respect to the intelligence that we know is out there; he's got to be in-depth with respect to what type of military action is going to be taken, and what is our current strategy? And how does this military strike impact that particular strategy?"

Kaine predicted that after a "very historic and important debate, lawmakers will "rally behind the principle that use of chemical weapons is wrong and it can't go unpunished." He echoed remarks by Secretary of State John Kerry earlier on the show that the president's decision to involve Congress offers the chance to present a united front to the world.

"We should not be sending servicemen and -women into military conflict if they don't have complete confidence that the nation's political leadership is behind them," Kaine said. "And so what this debate in Congress will do is it will educate the American public about the important principles at stake against use of chemical weapons. And it will help them understand, and help Congress come to a consensus about what needs to be done.

"...If we can reach a consensus, we will be much stronger as a nation," he concluded. "And the likelihood of success of our actions will be I think great."